Iron man Smith showing even more stamina at 32

Justin Smith was already recognized as an iron man before this season, but the 49ers defensive tackle is taking this stamina stuff to a new level in 2011.

Smith, 32, whose consecutive start streak of 161 games ranks fifth among active players, has played on 392 of the Niners’ 416 defensive snaps this season (94.2 percent), according to Pro Football Focus. Last year, Smith played on 74.5 percent of San Francisco’s snaps, according to web site.

Smith hasn’t missed more than seven snaps in a game this season and he never left the field in the Niners’ 25-19 win at Detroit, playing all 83 snaps. Last year, Smith missed eight or more snaps in 13 of the 15 games he finished (he was ejected in a Week 15 loss to San Diego and played 16 of 70 snaps).

According to PFF data, Smith played on 87.5 percent of the Niners’ defensive snaps in 2009 and was in on 93.4 percent of their plays in 2008, his first season in San Francisco.

Smith and defensive tackle Ray McDonald were regular workouts partners at San Jose State during the offseason. They also logged worked out at the team’s facility during the bye week.

Evidently that work is paying off.

In ticking off the names of players who have rarely left the field this season, defensive coordinator Vic Fangio noted Smith and McDonald’s stamina. McDonald has played on 390 of 416 snaps (93.8).

“… The unusual number is Justin Smith and Ray McDonald,” Fangio said. “They probably played a higher percentage of plays than most D-Lineman in this league.”

Smith made perhaps the play of the season when he stripped Eagles wide receiver Jeremy Maclin to seal a 24-23 win in Week 4. Smith tracked down Maclin and forced the fumble on his 68th and final play.

* Here’s the rundown of Niners who have played at least 100 defensive snaps this season. The data was provided by Pro Football Focus:

CB Tarell Brown: 414 of 416 (99.5 percent)

LB Patrick Willis: 410 (98.6)

CB Carlos Rogers: 409 (98.3)

Note: Willis missed his six plays at the end of the 48-3 win against Tampa Bay.

LB NaVorro Bowman: 406 (97.6)

LB Ahmad Brooks: 398 (95.7)

DT Justin Smith: 392 (94.2)

DT Ray McDonald: 390 (93.8)

S Donte Whitner: 273 (65.7)

S Dashon Goldson: 265 (63.7)

LB Aldon Smith: 201 (48.3)

Note: Smith has rushed the passer on 63.7 percent of his snaps (128 of 201). He’s defended the run of 49 plays and dropped back into coverage on 24 plays.

LB Parys Haralson: 187 (45.0)

S Reggie Smith: 174 (41.8)

NT Isaac Sopoaga: 142 (34.1)

S Madieu Williams: 142 (34.1)

CB Chris Culliver: 107 (25.7)

Note: Culliver didn’t play on defense until Week 4 against the Eagles. He played 69 of 83 snaps as the nickel CB against the Lions.